Machine for forming glass lens blanks



Jan. 8, 1935. A.N. CRAMER 1,986,917

MACHINE FOR FORMING GLASS LENS BLANKS Filed Sept. 28, 1951 2Sheets-Sheet 1 I I \e Y INVENTOR.

Patented Jan. 8, 1935 umr ao "STATES MACHINE FOR PATENT OFFIGE 1,986,917FORMING GLASS LENS nnmxs Albert N. Lramer, Toledo, Ohio, assignor, bymesne assignments, to Owens-Illinois Glass Company,'Toledo, Ohio, acorporation of Ohio Application September as, 1931, Serial No. 565,569

3 Claims.

,which, the finished lenses may be ground.

It is customary to roll the molten glass into flat sheets, and eachsheet, when cooled, is sub-= divided by cutting .into square portions ofsuitable size toiorm thelens blank. Such cutting is usually done byscratching the surface of the sheet and breaking through such scratch,which produces'rough fractured edges. 'Ijhese square portions are sortedby weight and re-heated to proper plasticity to mold into round formswith curved surfaces, from which the finished lenses are ground. There-heating operation is always diflicult and precarious. S6me glassesare very sensitive to the furnace atmosphere, and great caution must beexercised that a definite atinosphere is maintained. Other glassesinvariably change color in the re-heatingprocess, and a slight variationof temperature will vary the resultant color of such glasses.Manyfinished lenses are defective because the rough edges do not fuseduring the re-heating and molding 6perations. Furthermore, thedifllculty of accurately weighing each lens forming portion results inlens blanks of various thicknesses, which seriously complicates thegrinding operation, particularly when it is done in groups.

, It has been attempted to make spectacle lens, blanks by using a gobfeeder for subdividing the molten glass and then pressing a multiple oflens blanks from each 80 in a manner similar to the usual gob fedpressing operation. The result has been unsatisfactory because striaehas developed which makesthe lens blanks unfit for spectacle lenses. Itis characteristic of the vacuum process that the minimum amount ofstriae is developed when the molten glass is subdivided, and whatstriaemay develop will be in the direc tion of the flow of the moltenglass into the mold. Such strlae would be parallel to the 'surface ofthe lens blanks and therefore would not be ob-- 'jectionable inspectacle lensblanks';

One object of the present invention is to provide lens blanks with theminimum amount of striae and to control any strlae that may developlenses.

so that it is parallel to the surfaces ofthe finished An object of thepresent invention relates to forming lens blanks directly from themolten glass and similar in shape to the finished lenses.

Another object is to provide lens blanks formed and the mechanism (on.lei-.5)

directly from, molten glass and cut edges. I I

Another object is to provide lens blanks of uniform thiclmesses,whichhave been divided directly from the molten glass. Another object.is to provide curved surfaced lens blanks, which have been formeddirectlyfrom the molten glass. A further object is to provide lensblanks of predetermined weight, which have been formed 10 directly 'fromthe molten glass. 1

. Still another object isto provide meansfor devoid of rougn forminglens blanks from a mass of molten glass by molds rotating in a singleplane and in contact.with saidmolten glass.

Still another object is to provide a receptacle for molten glass inwhich the glass level is maintained to contact with a' rotating seriesof molds while the mass of molten glass isbeing reduced.

Other objects will be apparent hereinafter.

The present application discloses certain-subject-matter shown andclaimed in my copending application Serial No. 572,081, filed October30, 1931.

In the accompanying drawings:.

Figure 1 is a sectional view in elevation of the proposed mechanism.

Figure 2 is afragmentary plan view of the mechanism shown in Figure 1,and illustrates particularly the relation of i the rotating series Q ofmolds to the container for the moltenglass. Figure 3 is a'sectional-yiewshowing in detail the, valve 45.

Figure 4 is a fragmentary plan view showing the mechanism. for operatingthe cutting knife for opening and closing the mold sections.

-Figure 5 is a fragmentary sectional elevation of the cam and slideforopening and closing the mold sections. v I Y v Figure 6 is a fragmentarysectional elevation of the cam and slide for operating the cuttingknife. V Figure "7 is a. detail viewflin cross-section of the moldparts, showing particularly the mold--4 cavity and the vacuum passagesthereto. s

Figure 8 is a detail view in elevation of the rigidly secured moldsection and shows particularly the vacuum passages therein. Y In theaccompanying drawings is shown a pot 1 -for molten glass 2 which isheated, inla" manner not shown, to maintain any desired temperature. Asshown in Figure 1, said pot is provided with a gathering portion 3 andadjacent thereto a pivot 4. Threaded member 5 is-provided with a nut 6co-acting with the stop 7, and is connected to the lever 8, which isfulcrumed at 9, and which supports the-rear end of the potn'by meansofthe link 10. Adjustmentof the nut 6 is adapted to tilt the pot andthereby maintain the level of the molten glass in the gathering 1 thetrack structure, and thereby controls the plane in which the moldstravel. Attached to the track structure is a stop 14 adapted to positionthe forming machine in relation to the pot by co-acting with the wheel-15, upon which v the base 16 of said forming machine 'is mounted.

Superimposed upon this base is an annular column 1'7 about which themoving parts rotate. The moving parts comprise an annular hub 18, with aseries of projecting arms 19, at the ends of which are located glassforming molds 25. Suitable anti-friction bearings 20 are mounted on thecolumn about which the hub rotates. Mounted on said hub is an annulartoothed gear 21, in co-acting relation with pinion 22, mounted upon saidbase and actuated through a suitable speed reduction unit 23, by a motor24, or other suitable source of power.

The glass forming mold parts 25 comprise two mold sections. One section26 is rigidly secured to the arm 19, whereas the other section 2'? ispivotally mounted at 28 upon the rigidly niounted section. To move thetwo sections into and out of co-acting relation, there is provided asuitable resilient link 29, which connects the pivoted section to theslide 30, which is movable in the guide 31, by the roller 32, whichv iscontrdlled by the cam-path 33 of the actuating cam 34. The mold sectionsare held in closed contact while bein filled with the molten glass, anduntil the glass has cooled sumciently to form the lens blank. At apredetermined station the cam 34 opens the mold sections, and thelens'blank drops into a suitable receptacle or conveyor, not shown, for

handling the blanks to-the annealing process.

The rigidly mounted section 26, of the mold "parts 25, is provided witha relatively'large passage 35 in spaced relationv to the mold cavity 36.A relatively narrow passage 35A connects the larger passage with themold cavity when the mold sections are in closed contact. This narrowpassage is sufliciently wide to permit the atmesphere to be exhaustedfrom. the mold cavity, and is sumciently narrow that the molten glass isexcluded therefrom.

Superimposed over the rigidly mounted mold section is an exhaust chamber37, which is rigidly secured to the arm 19,.and connects the largepassages 35 with the rotatable portion 38 of a distributing chamber bymeans of the hollow tubular member 39. The non-rotating portion 40 ofthis chamber is secured to the column 17, and connected by means of thehollow passage 41 therethrough and piping 42 to an exhausting device 43,which is adapted to exhaust atmospheric pressure from said passages.This exhausting device is preferably mounted on the base 16, and isactuated by asuitable source of power, preferably a motor 44.

' interposed in the hollow tubular member 39 rosacrr is a valvemechanism 45, shown in detail in Figure 3, for opening and closing thehollow passage. This valve is normally closed by the exhaustedatmosphere of the distributing head. A cam 46, mounted on the column 17,is adapted to open said valve and thus exhaust the atmosphere from theglass forming mold, while the open bottom of the mold is in contact'withthe molten glass. N

A cut-oil knife 47, shaped to conform to the mold bottom, is providedfor each mold. This knife is mounted at 48, on the arm 19, to insureproper cutting contact with the fixed mold section 26. Knife operatingmechanism is pro-' vided by the link 49 attached to the slide 50,

which is slidable in the guide 51', and actuated by the attached roller52,-. mbunted in the campath 53 of the cam 54. Normally the knife isheld out of the path travelled by the mold, to insurenon-contactwith-the mass of molten glass in the pot '1. When the moldbottom contacts with the molten glass in the pot 1, itis submergedsufliclently to close the opening therein from the external atmosphere.The previously described valve 45 is now opened and the atmosphere isexhausted from the mold cavity 36, through the narrow passages 35A, andis replaced by the molten glass from the pot, which is forced into theexhausted cavity by the external atmospheric pressure exerted upon themass of molten glass. The narrow passages 35A confine the molten glassto the mold cavity. As the mold emerges from the mass of molten glass,the cut-off knife 4'! is actuated by the previously described cam 54,and that portion of the glass which is exterior to the mold cavity iscut of! and falls into the pot 1. It is noteworthy that the cut-offknifev is moved towards the rigidly mounted section of the mold, as aclean cut is thereby assured.

iVIodiflcations may be resorted towithin th scope and spirit of thisinvention.

What I claim is:

1. In glass forming machines, a container with molten glass therein,means for tilting said container to maintain the surface of said moltenglass at a constant level, and molds rotating in a plane inclined to andadapted to contact with the surface of said molten glass.

2. In a-machine for formmg glass lens blanks, a container with a mass ofmolten glass therein,

means for adjustably tilting said container, an inclined column, arotating series of molds adapted to rotate about said column andsuccessively contact with the surface of said molten glass, means forsuccessively filling said molds with said molten glass, means forremoving adhering portions of glass from the exterior of said molds asthey successively break contact with said molten glass, 6

and means for discharging the -glass from successive molds at apredetermined position.

3. Glass forming apparatus comprising, in combination, a tiltablecontainer for a pool of molten glass, molds open at their bottoms, meansfor moving the molds in a-path such that the mold bottoms travel in aplane inclined to the horizontal and to said pool, and are-brought bysaid travel into sealing contact with the glass in the pool, means forfilling the molds with glass from the pool while in said sealingcontact, and means for severing the glass in the inolds from the moltenglass in the container. V

ALBERT N. CRAMER.

